Well conditioning apparatus



ec. 28, 1948. M. SCHLUMBERGER 2,457,277

- WELL CONDITIONING APPARATUS Original Filed Aug. 1, 1941 4 Sheets-Sheet 1 IN VE TOR. MMU/5L 5mn/A155965@- TTEJYE'YS Dec. 28, 1948. ,M 'SCHLUMBEGER v 2,457,277V

WELL CONDITIONING APPARATUS Original Filed Aug. 1, 1941 4 Sheets-Sheet 2 INVEN TOR.

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Trama-ys Dec. 28, 1948. M. SCHLUMBERGER 2,457,277

WELL CONDITIONING APPARATUS v original Filed Agg. 1, 1941 4 sheets-sheet 5'- Dec. 28, 1948- M. SCHLUMBERGER WELL CONDITIONING APPARATUS '4 sheetssheet 4 Original Filed Aug. 1, 1941 llllllll'l INVENTOR. w/P622 50% M25/P65@ Patented Bec. 28, 1948 A UNIT ED STATE-fis 2,457,237?

Marcel Schlumberger, Paris,""F1`-ance; vested* i`n' the Attorney' vGeneral ofi the United lS-tatesi originalh application: August. 1v,F winfse'rial No. 405,024z Dividedant' this application`Junev2', 1945,.Serial N0..597,217 v l GClims. (ClI 16'6f-1r-)' 2 This application is aI division o1-l U; Si appliy when desiredin`v order to retract the'perfratin'g .cation Serial No. 4051324, liled August 1i 1941, means. fhfaccom'plisling' this'lpur-pose su'ch by` the present applicant, now Patent` MNo. vchaimbeieisfineorioratediinthe' apparatusithatiis 2,381,929, granted August' 14; 1945. lowered in tlielioleiandifis maintainedfatairela- The present invention relatestonew and im- 5 tivelvflow pressure; such"aseatmospheriefduring proved apparatus for sealing oilI the space b`e-y the lowering andilperfbrfatin'g operations; tThe tween the wall of a bore hole and-its casingiat operating pressure for" carrying on thelperforatany'd'esired depth or depths therein. inaJ is relieved "=vwheni*desired by 'e'stnb'li'sliing In the exploitation of oil wells drilled into `CerriIiiiinicatini'lcletiiveenfthelpressureoperating the earth, good" engineering practice requires 10 chamberantheipiessurerelieFchamberi that the space between the wall of the-borehole*- v lthei olloje'ct's"-and7 aiolifantages-1'lofftieiA 'invenandthe casing which is usually inserted therein i-tionf willlbeceme apparent 'fromthelfllowing debe sealed offat a predeterminedflocation or lo- .-taile'dldescriptin-taken'in-conjunction-with th cations in order to prevent the ow-o`ffuid faccompanyingiidrawiiigsfii'i'wfriiehzl l or gas therealong from one subterranean' bed to 15 Fig. 1 is a view in vertical section illustrating another. This is also essential in order to permit' appaliatiis-constructediaccordingf tbtl'iepresent the oil bearing layers to be exploited separately. invention"'ferperirati-ngf the casi-ng of f' alore I-Ieretofora it has been the practiceto pump "lholefand `forlinjectingisealiiigfmaterialitofftlie a suitable cement slurry through the casing to f space betweerllthe:lwalloftlfieboreholeiaridtlie the bottom of the bore hole and upinto the gmcasing: 1 space between the casing and the wall` of' the -L`Fig-2lf1is1as cross-sec-,tien'al vieWtaleIf-alng off the casing at pointsk near the bottom ofthe Tof bore hole, but it has not been found satisfactory 'ithe:normalinoperative"position: for sealing oli? the casing atk points at relatively g5L 3'illustrate'sitheperforatingfmeansshown great distances from the bottom of the bore' in Fig. I2vafter the perforation offtliecasiri'ghas hole. In the latter cases, the method is* costly gbeenfcomplreted;

because of the large quantities' of cement re- 7F11g2l4 showstl'ei-perforatiiigfmeans'off quired and the seals-producedareioften inelecin th'e'ret'ractedlpositnafter theiperl tig tive because' the cement isfrequently' not evenly 30.andsealingpfoperatlonshavei-fbefenfcomplet'd distributed about the casing. lhgsandi' are 1views fVei-tiealfs'eetln It is'an objectV of the presentinvention', acthroughiaLdrillCfholeeofftliel'1 Vprovedl apparatus,

cordingly, to provide new and improved'appara- {s'lovvfiri'g`aLnfiodiiedstructureforl p'erffrati-ng the tus for sealing ofthe-space between theA Wall ca'sing and iniectingisealiingm'aterial of the bore hole andv its casing which is free 35 `-Figsk 'Fand @laire-vertical'seotionsftliroiigha from thedisadvantages of the prior Iart notedz vvvdiillll'iole of? the'irriprovedapparatns, 'shwiiga above, and which is more simple, flexible andeco- Jmodi'cation off the construction illustratd in nomical in operation. Figs.: 5` andi GV-an'dfi-n whicl-iI apressureffrelif Another object of the inventionisto provide chamberisfiricorpoiratednew and improved apparatus'of the above char- 40;' Referring!toiFig.flZ---avkiore'holeI ID issliown acter which is adapted to perforate the casing, havingi a casing@ ifi@ therein-f'slightly`srrfalleriin and also to inject sealing'material'into the Space -xdiaimeters than: "tl'ief diameterf ioifthe` bore Hole rbetween the wall of the bore hole and the-casing Tim fornriingflanianr'mlarispacey i2'lb'etween tliewfall through the perforation or perforations' formed offthelldorevhle:iozandmgecagmg |11;A For contherein. 45 venience it will be assumed that it is desiredf-to A further object of the invention is to'provide formiaisealiinthespacerlZinTtieviinity'iofthe new and improved apparatusof the above'char- .upper boun'da'ryoi"anoiljbearlne` formaitinf i3 acter wherein the sealing material is disposed in traversed by theb'ore holel l0? Y al container located in the casing with the per- Witlimtn'ecasing lliialrld` iiithevicinity-offtl-e 'foratine and injecting means and iS' adaptedito wformationilaiis disposed'appa'ratus frperroratiiig be supplied therefrom t0 the injecting meansthe'casing'and for-'introducirigltiiesealing-mate- A more Speeie Object ,iS t0 provide, ina c011- frialf inte thevv spaceV l2J between the'f walioffte Vstruction of the character set forth abovergan -borefliole`5lll and'fthe casing H; 4This*app'ara'tlls assembly in'which a chamber is providedto-recomprises a, 'body Illimade. of,"ste'elor othersuitlease the pressure of the operating mechanism `fable-nr1,:rterial;having a' cylindricalchambel ence characters.

formed in the upper portion thereof within which is slidably mounted a piston I6 of relatively large area. The piston I6 is maintained normally near the top of the chamber I by means of a compression spring I1 which is seated in an annular recess I8 formed in the bottom of the chamber I5 and the upper end of which engages the lower face of the piston I6.

The lower portion of the piston I6 is formed as a coaxial cylindrical plunger I9 which is considerably smaller in diameter than the pistony I6, and which is slidably mounted within a bore 20 communicating at its upper end with the cylinder I5. The bore 20 communicates through a passage 2I with a cylindrical chamber 22 which extends transversely of the body I4 and which terminates in an opening 22a formed in the wall of the body I4. The portion of the chamber 22 which is nearest the kopening 22a is internally Athreaded at 23 to receive an externally threaded ,barrel 24 having al central bore 25 formed therein `within, which a cylindrical perforating and injecting element 26 is slidably tted.

I Located below the chamber 22 and communieating therewith through a passage 42a is a second 'chamber 22 in which is slidably mounted a perforating and injecting element 26. Corresponding parts in the lower element 26 and associated apparatus are designated by primed refer- Usually there will be a plurality of perforating and injecting elements located about the periphery of the body I4. For the sake of simplicity, however, only `two are shown in .Fig 1.

Referring now to Fig. 2, the injecting and per- .forating element 26 is slightly smaller in' diameter than the diameter of the chamber 22 and it has a laterally extending rear portion 21 which cooperates with the barrel portion 24 to limit theextent of movement of the perforating and injecting means26'. The rear portion 21' of the injecting and perforating element 26 is provided with a circumferential groove 28' within which is disposed suitable packing material 29 for provid-V l ing a tight joint.

In one side of the perforating and injecting means 26 is formed an aperture 30 providing .communication with -the hollow interior 3I' thereof. At the forward end of the perforating and injecting means 26' is provided'a closure member 32 within which are formed a plurality of longitudinal extending passages 33' and 34'. Mounted on the closure member 32 and secured thereby by means of a suitable screw 35is a.

punch 36' within which are formed a plurality of longitudinal grooves 31 and 38 which `are 1 ladapted to register with the passages 33 and 34',

respectively, permitting sealing material to be ,injected from the interior 3l' of the perforating and injecting means 26 through the passages 33 and 34 and the grooves 3'I and 38' into the I space I2 between the wall of the bore hole I0 and the casing I I, as described in greater detail hereinafter.

Formed in the piston I6 is a longitudinally extending passage 39 which communicates with a sol 4 in turn communicates with an aperture 42 formed in the wall of the bore 25 in the barrel 24.

The passage 4I continues downwardly through the body I4 and through the barrel portion 24 to an aperture 42 formed in the wall of the bore 25 in the barrel 24' located in the body I4 below the barrel 24.

In this embodiment of the invention, the apparatus is lowered into the casing II on a con- Ventional string oi drill pipe 43, at the lower end of which is formed a laterally extending flange 44 which is adapted to be rotatably received within a corresponding groove 45 formed in a head piece 46. The drill pipe 43 is provided with an aperture 4'I which is adapted to register with a laterally extending passage 48 formed in the head piece 46 when the string of pipe 43 is rotated with respect to the head piece 46 for the purpose of placing the hollow interior of the drill pipe 43 in communicationvwith the liquid Within the casing II. v

v At the surface of the earth, the string `of drill pipe 43 is connected to a length of exible tubing 49 towhich iiuid under pressureis supplied from suitable pumping means 50 located at the `surface of the earth.

In operation, the body I4 is lowered on the string of drill pipe 43 until the perforating and injecting elements 26 and 26 are located approximately at the depth ofthe upper boundary of the formation I3 where it is desired to form the seal. vA liquid cement mixture is then pumped from the pumping means 5I] through the flexible tubing 49 and through the string of drill pipe 43 into the chamber I5. At this time, of course, the aperture 41 in the drill pipe 43 will be out of registry with the passage 48 in the head piece 4,6.

The iuid pressure of the cement mixture with- `in the chamber I5 forces the piston I6 downy as shown inFig. 1. At this time it will be noted that the aperture 4I) in the plunger I9 is in registry with the aperture 4Ia in the wall of the bore 20 while the aperture 42 is infcommunication with the hollow interior 3I of the perforating and injecting means 26 through the aperture 30 therein. Accordingly, the cement mixture above thel piston I6 is forced through the passage 39, the aperture 40, the aperture 4Ia, the passage 4I, the aperture 42 in the perforating and injecting `means 26, the passages 33 and 34 therein and the grooves 31 and 38, respectively, in-the punch 36 into the space I2 between the wall of the bore hole III and the casing II. In similar fashion, cement is also injected through the perforating l and injecting means 26 into the space I2.

When a sufficient quantity of cement has been deposited in the space I2 to form a sealing ring therein, the operation of the pumping means 50 is stopped and the string of drill pipe 43 is rotated to bring the aperture 41 therein into registry with the passage 48 in the head piece 46. Fresh water is then pumped through the flexible tubing :aannam fg of the string of 'drill pipe-43-and removing any excess cement therefrom.

The-reduced pressure inthe lch-arrlber -|5fper mits the coil spring Il to restore lthepiston -lto its uppermostposi-tion, thereby reducing the oil .pressure in the bore 2U. When thisoccurs Aa force of considerable magnitude is applied tothe per-- forating andinjecting means 2S and '261by the pressure of the fluid contained inl-thebore hole '|0, which force results in the Iwithdrawal -of the perforating and injecting means 526 and -26 from the casing il and-into their normal positions, as shown in Fig. 2. -If the punches described below on the perforating and injecting means 25 and 2S' jam in the well casing -|f|, as will kusually occur, the .punches remain in :the well casing li and the remaining `partslof -the perforating and injecting means :26 and 26 take .the positions shown in Fig. 4.

yfrom one to two tons being required for a perforating pressure of about fteen tons.

The screw 35 which secures the punch 35 to the closure member 32 is made of relatively small section and is designed to break under a tensile stress which is less than that required to withdraw the punch 36 from the casing H. Accordingly, when a force is applied to restore the perforating and injecting means 26 to its normal position, the screw 35 will break leaving, the punch 3B' jammed in the casingl I, as shown in Fig. 4, forming an efective closure for preventing `fluid transfer between the interior of the casing and the space I2 between the wall of the bore hole I and the casing After the screw 35 has been broken, the perforating and injecting means 2/6' will yreturn to its normal retracted position within the chamber 22', as shown in Fig. 4. Similarly, the perforating and injecting means 26 will be restored to its normal inoperative position. The body I may then be moved to another position in the bore hole or it may be withdrawn therefrom.

Instead of using a conventional 'cement mixture, the sealing material might vcomprise a product having the property of setting by hydration. Such materials may be kept out of-contact with water by the novel perforating and injecting apparatus described above and would come into Contact with water only after having been injected into the space l2.

It is also possible to use as sealing materials substances which are normally solid at the temperatures usually encountered in wells, but which flow freely at higher temperatures. Lead base alloys such as mixtures of lead and tin have been found satisfactory for this purpose. Such substances can be injected into the space i2 while in the molten state and form an 'eiective seal upon solidication by cooling.

In Figs. 5 and 6 of the drawings is shown an apparatus in which two ingredients of the sealing material may be stored separately and .mixed together at lthe time of injection-into :the

mounted. lThefpiston I'I'G-is normally maintained in itsfuppermost yposition by fmeans offafcoil spring I'|' '|'-l,v1tl'-1e upper end of which i engagesthe lower face ofthe piston ||5 .and the .,lower'en'd '.of vwhich'.islseatedin the "bottomf of theichamher IAbovezithepiston H6 islocated a conventional 'type cartridge `lll; .which is adapted to vbeigm'ted .by vmeans of .a iilament 1||.9, one end "nf whichis grounded to the body ..|.|4.at .theipoint i223 `and the otherend of which is connected ito the vconductor |02 .in the-cable |06.

'lhe chamber `|15 communicates atnits lower 4extremity with a passage |'2| which in turnrcommunicates .with .a Ilaterally extending chamber |Z'2;formed.in the body M. Therchamber|22 has 'an opening at 'one end thereof tolnreceive rraA cylindrical :perforating and injecting :means` |23 `provided with a 'circumferential .groove |2`41'i-n the rear portion thereof in which is disposed suitfable ipacking material |25 for providingatight joint. The perforating and injecting'meansili2f3 is provided with a laterally extendingv passage |26 communicating kwith a longitudinal passage IZT'Which in .turn communicates with two'lat'erally 'extending passages |28 and |29 formed in the perforating and injecting meansv |23. "The lower `portion of 'the chamber 5, `the Apassage 12| `and the rear portion of the chamber '|22 r,are :Filled witha pressure transmitting-'duid such Aas oil, Awhich transmits pressure from the piston 1| L6 `to the perforating and injecting means 5123. Below `the chamber |22 and communicating therewith through a passage |2Ia isa -second chamber |22fhaving a perforatin'g and inj'ectim,r

means |23 slidably mounted therein. "The apparatus associated with the .perforating and-in- ,jectingrmean's |23 vis like that described above `in -connection with the perforating means |23 and;corresponding parts have been designatedb primed'reference numerals.

`When the perforating and injecting means "|23 kand 1:23V are in :the normal retracted position, .thepassages E28 and |29, and '|28' and |2`9"are vwhich includes ari-outer cylindrical casing `F34 threaded-1y ,secured "to the body H4, into v"the lower end of which is threadedv a'plug'l35. `With zin the casing |:34uis "formed a second casing '|536 which 'extendsfrom-the plug |35 to thebottom of the" body |`4 in the vicinity of the`passage"|`30. annularv piston |31 is s'lidably mountedwithin the casing |34 and a second piston |38 is slidably rmounted'withinthe casing |36. Withintheplug .|35 are Vformeel a' pair of passages #3a-and vHl) lwhich 'communicate 'with the interiors lof 'the Acasings |36 and |34, respectively. VThe twoin- :gredients comprising the `sealing material 4'are placedfabove the pistons |31 and 38,'respectively, -inftheicas'ings 1|34 and |36, respectively.

lflihe .top of the casing is closed "oifby means of a closure member'Ml providedwith'a suitable stu'filng box V|132 whichjpermits the cable 'F06 to be raised and'lowered within'ithefcasing The'fleXible-tubing 1| 9fwhi-chrsuppliesiuid under pressure from the pumping means 50 is connected to a suitable inlet |43 in the closure member ,4| Vand-a conventional pressure indicating 1nstrument |44 is provided for indicating the pres- -sureof the liquid Within the casing In operation, the body I|4 is lowered to the approximate depth where the seal is to be made 'and is. brought to rest at that position. The

n|28 and |29 in the perforating and injecting lelement |23 into registry with the passages |36 and |3 I, respectively, and the ,passages |28 and :|39 in the element |23 into registry With the passages |36 and |3I, respectively.

Pressure is now applied to the liquid in the bore hole by means of the pumping means 50 at the-surface of the earth. This forces the liquid within the casing II through the apertures |38 and |40 in the plug |35 and against the pistons `|38 and |31, respectively, moving them upwardly and forcing the respective ingredients of the seal- ,ing material contained in the casings |36 and |34, respectively, through the passages |36 and v| 3|, respectively, in the body ||4 through the .passages |28 and |29, respectively, in the perforating and injecting means |23. From thence, the sealing material flows through the passage l|21 in the perforating and injecting means |23 -and out of the passage |26 into the space I2 between the wall of the bore hole I and the casing In similar fashion, sealing material is forced 'through the passages |30 and |3I, respectively, vand the passages |28 and |29', respectively, to

the passage |21 in the perforating and injecting =-means |23. This may be containued until the pistons |38and |31 have reached their uppermost v.limits of travel, which event will be indicated by an increase of pressure at the pressure indicating instrument |44.

In order to retract the perforating and injecting elements |23 and |23 from the casing it is necessary to release the powder gases from the Mchamber' I5. =to the cable |06 to break the head piece |01, there- This is done by applying tension by permitting the powder gases to escape through 4the `passage |68 and the passages I2 to the liquid in the casing This permits the coil spring |1 to restore the piston ||6 to its normal position,

releasing the pressure on the oil contained in the chambers |22 and |22 and permitting the perforating and injecting elements |23 and |23' to be .withdrawn into their normal retracted positions by the resulting pressure differential.

For the sake of simplicity, only two perforating and. injecting means |23 and |23 have been shown in Fig. and described above. In actual practice, there may be a plurality of such perforating and injecting means disposed about the circumference Aof the body ||4, each being actuated by the oil in the chamber ||5, and each .adapted to receive the sealing material ingredients from the casings |36 and |34.

4The apparatus described above in connection with Fig. 5 enables a sealing material to be employedV which comprises two or more substances which, when mixed, tend to harden rapidly. For example, a cement which sets relatively slowly might be placed above the piston |31 in the casing |34 and another substance such as, for example, sodium silicate, which when added to cement causes it to harden rapidly, might be placed above the piston |38 in the casing |36. In similar fashion, liquid latex and an acid might be used as the ingredients of the sealing material since they tend to produce a relatively solid substance when mixed together. Other suitable sealing materials will readily suggest themselves to those skilled in the art and they need not be set forth herein.

In Figs. 7 and 8 is shown a modiiication of the apparatus shown in Figs. y5 and 6, comprising a special device for controlling the return stroke of the perforating and injecting means.

Punch |60 and perforating and injecting means |6| are adapted to jam in the casing when kthe perforating and injecting means returns to its normal position, so as to plug the hole previously perforated by this punch. The special device for controlling the return stroke of the periorating and injecting means comprises a chamber |62, of appropriate and rather large dimensions, provided in the body of the apparatus, above the powder combustion chamber IIE. The pressure inside said chamber |62 is Very low (atmospheric pressure for example) in relation to the pressure inside the bore hole. To obtain this result the chamber is tightly closed before the apparatus is lowered in the bore hole. For controlling the return stroke of the injecting means, this chamber is brought into communication with the powder combustion chamber. In this way the combustion gases then expand in the said chamber until a pressure is reached which is much lower than the pressure of the mud inside the bore hole. At this moment, due to this diierence of pressure, the perforating and injecting means I6| is thrust inside chamber |22 carrying with it punch |60 which jams in the casing. The shaft of the punch then breaks, and the perforating and injecting means continuing its movement returns completely inside chamber |22 (see Fig. 8).

The device for bringing chamber ||5 into communication with chamber |62 may be of any type. In the iigure, shaft |63 which is attached to the supporting cable |66 comprises a Weak point |64 and is chambered out in its center |65. The upper end of said shaft |63 goes through a ange |66, integral with a plate |61 which closes the upper part of the chamber |62, said upper end being located underneath another chamber |68, communicating with the inside of the well through holes |69. A rubber sleeve |10 tightly joins shaft |63 and flange |66. After the perforation followed by cementing, which is brought about by the ignition of the powder in chamber I I5, the device is brought back to its normal position by means of strong traction on the cable, which has the effect of breaking shaft |63 at the level of the weak point |64. This brings chamber I5 into registry with chamber |62 by means of passage |65 and the perforating and injecting means then returns to its normal position as indicated above. The apparatus remains held by the cable by means of the upper end of shaft |63 abutting against the cover I1| of the apparatus.

The mode of operation is similar to that described in connection with Figures 5 and 6 and the same reference numerals indicate corre-1 sponding parts in Figures and 6 and Figures 7 and 8. The particular improvement disclosed in Figures 7 and 8 has to do with the relation of the expansion chamber |62 to the ehplosion chamber1 H5 and the means by which the two are placed in communication after the firing so that the injecting tool itl is forced back into its chamber |22. The pressure wit-hin the eXpansion chamber H52 is substantially less than that of the drilling fluid in the bore hole to which the injecting tool it is subjected.

The several specific embodiments described above are intended to be illustrative and not restrictive of the invention. Those embodiments are obviously susceptible of numerous changes in form and detail within the scope of the appended claims.

I claim:

l. In `an Iapparatus for working inside a bore hole, the combination of a tool adapted to be vdriven towards the wall of the hole, an explosion chamber containing an explosive charge, the eX- plosion of which actuates the tool, igniting means for said explosive charge, means for controlling said igniting means, an expansion chamber, and means for making a communicati-on between this expansion chamber and said explosion chamber, so as to control the return stroke of the tool after the Working stroke has been effected.

2. In an apparatus for working inside a bore h-ole, the combination of a tool adapted to be driven towards the wall of the hole, an explosion chamber containing an explosive charge, the eX- plosion of which actuates the tool, igniting means for said explosive charge, means for controlling said igniting means, a fluid-tight chamber having an internal pressure substantially below that of the bore hole liquid, and sealed off from said explosion chamber, and means operable after the explosion of said charge for establishing communication between said expansion chamber and said explosion chamber, so as to control the return stroke of the tool after the working stroke has been effected.

3. In an apparatus for working inside a bore hole, the combination of a tool adapted to be driven towards the wall of the hole, a pressure chamber for actuating the tool, means for rendering said pressure chamber eifective to drive the tool towards the wall of the bore hole, an exparisien chamber, and means for making communication between said expansion chamber and said pressure chamber, so as to control the return stroke of the tool after the working stroke has been effected.

4. In an apparatus for Working inside a bore hole, the combination of a body member having a rst chamber therein and at least one bore communicating with said chamber, a tool in said bore, reciprocably movable towards and away from the wall of the hole, piston means slidably mounted in said chamber, pressure transmitting fluid in said chamber on one side of said piston means, an explosive charge in said chamber on the other side of said piston means, means for igniting said explosive charge to cause said tool to be driven towards the wall of the hole, an expansion chamber in the body, and means for making communication between said expansion chamber land said nrst chamber, so as to control the return stroke of the tool after the working stroke has been effected.

5. In an apparatus for working inside a bore hole, the combination of a body member having a first chamber therein and a plurality of laterally extending bores communicating with said chamber, a tool in each of said bores, reciprocably movable towards and away from the wall of the hole, each of said tools including casing perforating means and cooperating fluid outlet means, piston means slidably mounted in said chamber, pressure transmitting uid in said chamber on one side of said piston means, an explosive charge in said chamber on the other side of said piston means, means for igniting said explosive charge to cause said tool to be driven towards the wall of the hole, a container of fluid material in said body, means providing communication between said container and said tool fluid outlet means during the working strokes of said tools, means to apply pressure to the fluid material in said container to cause flow thereof from said tool fluid outlet means, an expansion chamber in the body, and means for making communication between said expansion chamber and said first chamber, so as to control the return. stroke of said tool after the working vstroke thereof has been eifected.

6. In an apparatus for working inside a bore hole, the combination of a tool adapted to be driven towards the Wall of the hole, said tool including casing perforating means and cooperating fluid outlet means, a pressure chamber for actuating the tool, means for rendering said pressure chamber effective to drive the tool towards the wall of the bore hole, a container of fluid material, means providing communication between said container and said tool fluid outlet means, means to apply pressure to the fluid material in said container to cause flow thereof from said tool fluid outlet means, an expansion chamber, and means for making communication between said expansion chamber and said pressure chamber, so as to control the return stroke of said tool after the working stroke thereof has been eifected.

MARCEL SCHLUMBERGER.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,120 Schlumberger Sept. 29, 1936 2,015,873 Schlumberger Oct. 1, 1935 2,055,506 Schlumberger Sept. 29, 1936 2,119,361 Schlumberger I- May 31, 1938 

